In 35 pregnant women threatening premature labour and cervic dilatation indicated therapy by a beta-mimetic compound (fenoterol) for tocolysis. 17 patients (group I) got fenoterol-monotherapy; in 18 patients (group II) fenoterol was combined with the cardioselective beta-1-blocking agent metoprolol. There were no differences in age, bodyweight and time of gestation in both groups before therapy; also the obstetric states--as compared by pelvic score (Bishop) and tocolysis index (Baumgarten)--were nearly identical. Efficiency of tocolytic therapy was evaluated by prolongation index (Richter) and tocolysis-success-score (Weidinger). Statistical analysis comparing these parameters in both groups showed no significant differences. Heartrate, however, was significantly (p > 0,005) lower in patients treated by fenoterol and metoprolol, thus indicating less cardial stress induced by fenoterol. In conclusion the combination of the semiselective beta-2-stimulating compound fenoterol with the beta-1-blocking agent metoprolol is proposed for tocolytic therapy because of less cardial stress but identical tocolytic efficiency as compared with fenoterol-monotherapy.